Electron collisional excitation cross sections for Fe III and Fe VI and iron abundances in gaseous nebulae

Garstang, Roy H.; Robb, W. D.; Rountree, S.P.

doi:10.1086/156152

Cited by 53 publications

(42 citation statements)

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“…At electron densities of 10 7 cm −3 the emissivity ( erg s −1 cm −3 ) of the [Fe III] λ4659 forbidden line is proportional to the Fe III ions number density, n III , times electron density, while at higher density the emissivity becomes proportional to n III (Garstang et al 1978). There are several quantities that are difficult to calculate and hence introduce uncertainties in estimating the power of the line.…”

Section: The Freely Expanding Windmentioning

confidence: 99%

The interaction of the eta carinae primary wind with a century old slow equatorial ejecta

Soker¹,

Kashi²

2012

New Astronomy

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We argue that the asymmetric morphology of the blue and red shifted components of the outflow at hundreds of AU from the massive binary system η Carinae can be understood from the collision of the primary stellar wind with the slowly expanding dense equatorial gas. Recent high spatial observations of some forbidden lines, e.g. [Fe III] λ4659, reveal the outflowing gas within about one arcsecond (2300 AU) from η Car. The distribution of the blue and red shifted components are not symmetric about the center, and they are quite different from each other. The morphologies of the blue and red shifted components correlate with the location of dense slowly moving equatorial gas (termed the Weigelt blob environment; WBE), that is thought to have been ejected during the 1887 -1895 Lesser Eruption (LE). In our model the division to the blue and red shifted components is caused by the postshock flow of the primary wind on the two sides of the equatorial plane after it collides with the WBE. The fast wind from the secondary star plays no role in our model for these components, and it is the freely expanding primary wind that collides with the WBE. Because the line of sight is inclined to the binary axis, the two components are not symmetric. We show that the postshock gas can also account for the observed intensity in the [Fe III] λ4659 line.

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Section: The Freely Expanding Windmentioning

confidence: 99%

The interaction of the eta carinae primary wind with a century old slow equatorial ejecta

Soker¹,

Kashi²

2012

New Astronomy

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“…Quinet et al 1996), Col. 4 the line intensities measured in the Orion nebula relative to He I λ6678, multiplied by 100 (Verner et al 2000), Col. 5 the relative intensities measured in HS 0328+05, Col. 6 the log of the ratio of the intensities observed in HS 0328+05 and Orion. (Garstang et al 1978). …”

Section: Narrow Emission Lines In the Range 5080-5430åmentioning

confidence: 99%

The “red shelf" of the H$\boldmath\beta$ line in the Seyfert 1 galaxies RXS J01177+3637 and HS 0328+05

Véron

Gonçalves

Véron-Cetty

2002

A&A

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Abstract. A few Seyfert 1s have a Hβ profile with a red wing usually called the "red shelf". The most popular interpretation of this feature is that it is due to broad redshifted lines of Hβ and [O III]λλ4959, 5007; we have observed two Seyfert 1s displaying a "red shelf" and showed that in these two objects the main contributor is most probably the He I λλ4922, 5016 lines having the velocity and width of the broad Hβ component. There is no evidence for the presence of a broad redshifted component of Hβ or [O III] in any of these two objects.

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“…Emission lines arising from transitions among the finestructure levels of the 3d 6 configuration of Fe III are widely observed in the optical spectra of astrophysical sources, including planetary nebulae, H II regions, and quasars (see, for example, Garstang et al 1978;Keenan et al 1993;Ryans et al 2003;Mesa-Delgado et al 2009 and references therein). These Fe III transitions are also important tracers of Fe abundance in the case of H II regions and lowly ionized planetary nebulae, where they are often the only ionization state of Fe detected in the optical band.…”

Section: Introductionmentioning

confidence: 99%

“…These Fe III transitions are also important tracers of Fe abundance in the case of H II regions and lowly ionized planetary nebulae, where they are often the only ionization state of Fe detected in the optical band. Garstang et al (1978) first noted the diagnostic potential of optical Fe III lines; subsequently, several authors have generated theoretical electron temperature (T e ) and density (N e ) dependent emission-line intensity ratios for this ion, and used these to determine plasma parameters for nebular sources (for example, Keenan et al 1993Keenan et al , 2001Bautista et al 2010, and references therein.). However, there are longstanding inconsistencies between electron densities derived from different Fe III ratios, as well as discrepancies with values of N e determined from other species such as OII, SII, and ClIII with similar ionization potentials to Fe III, which hence should originate in nearby regions of the nebular plasma.…”

Section: Introductionmentioning

confidence: 99%

Emission Line Ratios of FE III as Astrophysical Plasma Diagnostics

Laha

Tyndall

Keenan

et al. 2017

ApJ

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Recent, state-of-the-art calculations of A-values and electron impact excitation rates for Fe III are used in conjunction with the Cloudy modeling code to derive emission-line intensity ratios for optical transitions among the fine-structure levels of the 3d 6 configuration. A comparison of these with high-resolution, high signal-to-noise spectra of gaseous nebulae reveals that previous discrepancies found between theory and observation are not fully resolved by the latest atomic data. Blending is ruled out as a likely cause of the discrepancies, because temperatureand density-independent ratios (arising from lines with common upper levels) match well with those predicted by theory. For a typical nebular plasma with electron temperature = T 9000 e K and electron density = -

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Electron collisional excitation cross sections for Fe III and Fe VI and iron abundances in gaseous nebulae

Cited by 53 publications

References 0 publications

The interaction of the eta carinae primary wind with a century old slow equatorial ejecta

The interaction of the eta carinae primary wind with a century old slow equatorial ejecta

The “red shelf" of the H$\boldmath\beta$ line in the Seyfert 1 galaxies RXS J01177+3637 and HS 0328+05

Emission Line Ratios of FE III as Astrophysical Plasma Diagnostics

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